Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
  • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
  • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
  • F02M45/08—Injectors peculiar thereto
  • F02M45/083—Having two or more closing springs acting on injection-valve

Definitions

• the invention relates to a fuel injector for internal combustion engines of the type defined in the preamble of claim 1. Such an injector with
• the intermediate disc and the intermediate bushing have the advantage that the tolerance range of the advance stroke of the valve needle, which is to be kept within narrow limits, is determined solely by the manufacturing tolerances on the pressure element and on the nozzle needle.
• the forward stroke can therefore be measured precisely and by grinding the
• Stop of the valve needle (which is generally formed by the free end of the valve needle can be adjusted. Measurement tolerances and / or changes occurring during operation or during assembly no longer affect the size of the advance stroke.
• the shoulder fixed to the housing for supporting the second closing spring is created by a stepped design of the spring chamber, preferably as an axial stepped pocket bore.
• the second closing spring rests on an annular disk against the annular shoulder formed between the bore sections with different bore diameters.
• the pressure pin protrudes through a central opening in the ring disk and is acted upon by the first closing spring on the face side.
• the two closing springs are graduated according to the two different diameters of the spring chamber.
• the fuel injection nozzle according to the invention with the characterizing features of claim 1 has the advantage that the outer diameter of the nozzle holder can be made smaller without loss of strength.
• the closing springs are identical in construction, the spring chamber has a constant diameter over the entire length, which can be kept relatively small.
• the closing spring which is close to the nozzle body, is supported by means of a cross bolt crossing the spring chamber, so that the spring chamber available for the first closing spring can thus be fully used.
• the cross bolt is inserted into a radial blind hole crossing the spring chamber and seals the spring chamber by means of an O-ring.
• the transverse bolt is fixed in the radial blind bore by a centering piece designed as a spring plate, by means of which the second closing spring, which is close to the nozzle body, is supported on the transverse bolt.
• the drawing shows a longitudinal section of a fuel injector for direct injection internal combustion engines.
• the injection nozzle shown in longitudinal section in FIG. 1 has a nozzle body 10 which, together with an intermediate disk 11 lying on the end face, is guided by a nozzle
• Union nut 12 is clamped to a nozzle holder 13.
• a valve needle 14 is axially displaceably mounted in the nozzle body 10 and cooperates with an inward-facing valve seat in the nozzle body 10 and controls a plurality of spray openings 15 located upstream of the valve seat.
• the guide bore 16 of the valve needle 14 in the nozzle body 10 is, as usual, expanded at one point to a pressure chamber, in the area of which the valve needle 14 has a pressure shoulder.
• the pressure chamber is via a channel 17 running in the nozzle holder 13 and only partially shown, with a nozzle 18 Nozzle holder 13 for connecting a fuel delivery line leading to a fuel injection pump.
• valve needle 14 The fuel pressure applied to the pressure shoulder of the valve needle 14 pushes the valve needle 14 upward against the graduated force curve of a closing spring arrangement described in the following, consisting of two helical compression springs, the valve needle 14 executing a preliminary stroke in a pre-injection phase and a residual stroke in a main injection phase, in which fuel via the Spray openings 15 is sprayed out.
• a spring chamber 19 is arranged coaxially with the valve needle 14, which is designed as an axial blind bore and is closed on its open end face by the intermediate disk 11.
• a "first closing spring 21 and a second closing spring 22 are arranged in series in the spring chamber 19.
• the first closing spring 21, which is more distant from the nozzle body 10, acts continuously on the valve needle 14 in its closing direction via a pressure pin 23.
• the first closing spring 21 is supported by a disk 20 on the base 30 of the spring chamber 19 and via a spring plate-like support element 31 on the end face of the pressure pin 23.
• the support element 31 has on its end face a recess 32 which receives the end face of the pressure pin 23 in a form-fitting manner guided axially displaceably and abuts the free end of the valve needle 14.
• the intermediate bush 24 is guided axially displaceably in the intermediate disk 11 coaxially to the valve needle 14 and bears a stop 25 and a counter-stop 26.
• the stop 25 formed by a radial annular shoulder cooperates one of a same ichen shoulder formed on the intermediate plate 11 to limit the total stroke of the valve needle 14 together.
• the from the end face of the intermediate bushing 24 Counter stop 26 formed interacts with a stop 28 formed by the end face of valve needle 14 to limit the forward stroke of valve needle 14.
• the second closing spring 22, which is constructed identically to the first closing spring 21, is in the spring chamber 19 of the first closing spring
• the second closing spring 22 is supported by a spring plate 29 on the intermediate bush 24, which is thereby placed in the closed position of the valve needle 14 on the end face of the nozzle body 10, and with its other end, the second closing spring 22 presses via a centering piece 33 designed as a spring plate against a cross bolt 34 crossing the spring chamber 19.
• the cross bolt 34 which has a radial through opening 35 in the region of the spring chamber 19
• Passage of the pressure pin 33 and a receptacle 36 for the centering piece 33 is inserted into a radial blind bore 37 which crosses the spring chamber 19.
• a sealing ring 39 which is located in an annular groove 38 of the transverse bolt 34 and is designed as an O-ring, seals the spring chamber 19.
• the transverse bolt 34 is fixed in the radial blind bore 37 by the contact pressure of the second closing spring 22, which secures the transverse bolt 34 in the spring chamber 19 against transverse displacement via the centering piece 33 and the receptacle 36.
• the spring chamber 19 is still connected via a channel 40 to a connecting nipple 41 for a leak oil line.
• the valve needle 14 performs a preliminary stroke h v , in which only the first closing spring 21 acts as a counterforce.
• a limited pre-injection quantity is injected from the injection openings 15.
• the preliminary stroke h v is ended when the stop 28 on the valve needle 14 comes to rest against the counter stop 26 of the intermediate bush 24.
• the valve needle 14 remains in this position until the rising one Fuel pressure now overcomes the opposing forces of both closing springs 21, 22. Thereafter, the valve needle 14 together with the intermediate bush 24 is moved further in the opening direction until it has completed its total stroke after the remaining stroke h v . This is limited by the counter stop 27 on the
• the invention is not limited to the exemplary embodiment described.
• the intermediate disk 11 Juch can thus be formed from two individual disks, of which the lower individual disk has a larger inner diameter than the upper one.
• the counter-stop 27 for limiting the total stroke of the valve needle 14 is formed by the area in the upper single disk not covered by the lower single disk.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6367434

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (2)

Citations (2)

• 1988
  • 1988-11-18 DE DE3839038A patent/DE3839038A1/de not_active Withdrawn
• 1989
  • 1989-10-19 WO PCT/DE1989/000667 patent/WO1990005844A1/de active IP Right Grant
  • 1989-10-19 EP EP89911536A patent/EP0444053B1/de not_active Expired - Lifetime
  • 1989-10-19 DE DE8989911536T patent/DE58903686D1/de not_active Expired - Fee Related
  • 1989-10-19 JP JP1510760A patent/JPH04501752A/ja active Pending

Patent Citations (2)

Non-Patent Citations (1)

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